EGR insufficient flow. 1.9 BJB

[andy-fisher]

Well, having had an engine light on for a few months now I finally got around to trying to sort it out. The fault code indicated EGR insufficient flow. I admit I should have checked the EGR valve before ordering a new one but as I sourced a brand new valve for £45 I thought I'd go for it. 

 

I removed the old valve (A 5mm ball ended Allen key enables removal of the bottom bolt with relative ease) to be surprised that it wasn't bad at all considering the car has done 179,000 miles and the valve has never been cleaned before. It also held a vacuum to both the EGR and ASV. 

After fitting the new one anyway (having checked it held a vacuum first as it was a cheap valve) I cleared the stored fault code and went for a little drive. After about 150 miles, the light came on again. Same fault code as before. 

 

Any advice on what to try next? Shall I just clean up the old one and put it back on?

 

I was going to change the vacuum lines but unsure if I should bother.  The pipe that feeds the exhaust gases to the valve was clear at the valve end but I didn't remove it completely to check the other end.

 

Is there any way to check the vacuum solenoid block is functioning correctly? The ASV definitely works when turning off the engine but not sure about anything else. If I remove the multi pipe thing after turning off the engine I can hear that there was a vacuum applied.

 

How does the car measure the flow of exhaust gases to determine that the flow is low?

 

Sorry for the long post and thanks in advance for any ideas.

Edited 18 April, 2017 by andy-fisher
Some spelling mistakes. Probably many more.

[satire111]

As I understand it, the air flow meter along with the engine e.c.u. are involved with the egr flow basically when the egr valve is opened the inlet airflow should alter and be within set parameter's that the engine e.c.u. will expect. Engine speed and engine load will also be programmed within the engine e.c.u. to start the opening of the egr

I would be checking the air flow meter for cleanliness, spray it with brake cleaner if it looks sooty or dirty  also can you check to see that there isn't a leak from the exhaust side along the egr pipe through the water cooled unit and up to the egr unit good luck and let us know how you get on

[andy-fisher]

Thanks for the pointers. Hopefully I will get some time this weekend to have a look.

 

I will post up my fix if I eventually find one.

[andy-fisher]

Well today I took out the MAF sensor. I left the main body in place and just took out the sensor and when I removed it there was a cloud of dust and dirt. I gave it a quick clean with a q tip, put it back and reset the faults. I have only done approx 20 miles (approx 4 engine starts) and the light has not come on yet. A good test will be my commute to work tomorrow. If it doesn't come on again over that distance then I will call it fixed.

 

I really wish I had removed my EGR before ordering a new one as the old one was not bad at all. It only cost £45 instead of the ECP price of £255 but if it turns out the fix was one Q tip and a 99p tin of carb cleaner then I still feel foolish for not doing such a simple job in the first place. I just can't be without the car for long so got spares in advance.

 

Just for other people's information, my cars EGR feed is direct from the exhaust manifold with no cooler (2004 with a BJB engine) My Renault Scenic has a cooler as I changed both that and the EGR when I got the same fault on that car. Not tested it yet as the battery is goosed now. I think I will check the MAF sensor on that before I start it up again but after 14 months of not being used I think the rest of it will need attention now.

 

I guess once I've cleaned the old valve I have a spare for future use.

 

If it turns out that it is fixed then I will look at posting up a quick guide.

 

Many thanks to satire111 for the advice.

[doho121]

Thanks for the advice - this error has been bugging me but my EGR is awkward to remove so I cleaned it and reset. It all seems to be working but fault still exists. I'll look at the MAF later and see how that goes. Thanks for the advice.

[andy-fisher]

Unfortunately the light has come back on and the same fault code is back (16785/P0401)

 

It still only took about 200 miles to come back again which is how it's been since I first got the fault. It may still be the MAF sensor and cleaning was not the way forward.  It's a shame they are so expensive. I did try cleaning it again but it came back on today.

[chimaera]

I don't know if you've come across this page already but it might be of use to you: http://wiki.ross-tech.com/wiki/index.php/16785/P0401/001025

[andy-fisher]

1 hour ago, chimaera said:

I don't know if you've come across this page already but it might be of use to you: http://wiki.ross-tech.com/wiki/index.php/16785/P0401/001025

 

I have but thank you.

[doho121]

I cleaned my EGR and the MAF, light continues to reappear especially when the engine is cold and driving at low speeds. Any long term downside to leaving it this way?

[andy-fisher]

I've not noticed any major down sides yet apart from what I think might be a slight loss of power.  I've had the light on for about 8 months now and it passed an MOT with it on (mentioned as an advisory).  I would rather find the fault and fix it though.  Just ordered some new vacuum pipes to try that as was wondering if the pipe is collapsing when under a vacuum as they have been on my car for over 12 years.  They are cheap enough and can't do any harm changing old for new as far as I know (gone for silicone which I hope is a good choice).  My current plan is to try the new vac lines, if no joy then get a known working vacuum solenoid (2nd hand), 2nd hand MAF and then if all fails, get it mapped out.  If I ever find a solution I will let you all know.

[doho121]

Yeah we fail NCT here if there's a light so I zapped it in the test centre car park. I would like it fixed too. My car has a whine that I thought was an aging turbo but now I'm beginning to think there could also be an air leak somewhere. Keep me posted on how it goes for you.

[andy-fisher]

I have a bit of turbo whine, it's had it for many years and miles now so I'm not worried about that and the light is a relatively recent thing so I don't think my turbo noise is linked. I'll keep you posted on any progress I make.

[andy-fisher]

New vacuum lines on (well, nearly as I ran out of 3mm but have 5mm left. Seems I mixed up my measurements)

 

Time to reset any pending code and give it a go. 

[andy-fisher]

After approx 230 miles the light was back on again (3 engine starts). Ordered some more silicone hose (3mm ID) to finish of the job I started last weekend. I've found a solenoid block on eBay but undecided if I should go for that first or the MAF. My N/S/F Spring snapped today so I think my EGR fault will go on hold for a while.

Edited 11 May, 2017 by andy-fisher

[andy-fisher]

Today I fitted a brand new MAF sensor. Reset the codes and I will see how it goes. I did notice the new MAF sensor has a resistor which appears to be missing from the old one so maybe it was that all along. It's not loose in the housing so I'm not sure where it's gone which concerns me.

[andy-fisher]

Well, that's not worked. last thing I'm trying is a new (or maybe 2nd hand) vacuum solenoid. Then if that fails I'm out of ideas other than getting it mapped out.

[andy-fisher]

A used vacuum solenoid block fitted today, codes reset and now time to test it out. I've done about 20 miles with 2 engine starts so far but from experience, it will be a while before I have an answer. I intended to finish the vacuum lines off this weekend but the wrong size turned up (different supplier send 2mm ID tube). Hopefully the correct size is on its way.

 

I realise I have been stating the number of engine starts and that is because if I reset the fault codes, it doesn't seem to matter how far I drive on the first journey, the light doesn't come on. It takes 3-4 journeys before it comes on. My findings so far are that if I reset the codes then drive to work (170 miles) it's fine. Do my working week shopping trip and it will be fine, take a couple of short trips into town at some point in the week and it will come on during one of those. Supermarket is about 10 miles away as is the local town.

 

Anyway, I will keep you all posted on the result. As I like messing with the car I may start putting the old parts back on to make sure I have narrowed down the actual cause of the fault.

[andy-fisher]

Initial signs are good (sort of).  The warning light has not returned and I would have expected it to by now.  However, I now have quite bad hesitation and juddering on gentle acceleration, normally when going up hill at around 40-50 mph in 5th gear.  It feels like the engine is stuttering like fuel starvation or maybe the EGR is open when it shouldn't be.  Fuel consumption seems to have increased a little which may be due to the fact I can only get the car to behave if I put my foot down.  Power seems fine when I push the pedal that little bit harder.  To try to figure out what's happening now, I have refitted my old MAF sensor which has made no difference so far (no engine light and still feels like it's being choked up).  My next step is going to be to put the old EGR valve back on as I don't think it was faulty in the first place.  I think I'm on the right lines with the vacuum solenoid but I may need to invest in a new one rather than a used one unless someone has a better idea as to what may be happening now.  To be honest, I could probably live with just putting all the old stuff back on and having a warning light as it performed well like that.

[andy-fisher]

Update time. 

 

I have refitted the old EGR valve with new gasket and seal. I've not fully tested it yet but initial signs are good. I've not managed to get the same hesitation I was getting before but I've only done a short drive and re-checked the security of the bolts.  My commute should highlight any issues and I will report back.

 

As the car stands now it has its original MAF sensor and EGR valve back on but a 2nd hand vacuum solenoid with silicon vacuum lines.

 

I think the old saying, 'Buy cheap, buy twice' has been the issue here with a Chinese EGR valve causing the hesitation. Most annoying though is the fact I didn't even need a new valve despite advice all over the Internet.

 

I hope my experiences will help some one else out. I would have made a guide but the vacuum block is so easy to change there's little point unless somebody wants a guide.

 

If your after a new vacuum solenoid rather than 2nd hand then the best price I've had so far is from [email protected] followed by Darkside.

 

Part number: 6Q0906625E

 

 

Edited 7 July, 2017 by andy-fisher
My usual spelling mistakes.

[wiilydog]

Did you test your old EGR with a vacuum pump to see if it is holding a vacuum as they do wear out as if it doesn't open there will be no hesitation.

[andy-fisher]

I tested it by forcing the valve open and then sticking my finger over the vacuum pipe connection and then letting the valve try to close again. It didn't, it stayed open. 

 

Also, if the valve doesn't open then I would get an isufficient flow fault which I don't have now.

 

i believe that the Chinese valve was opening too easily (less Spring tension) which was causing the hesitation as it was opening too much for given parameters. With the newer valve fitted and the old vacuum block I still got the fault code. Newer valve and replacement vacuum solenoid, no fault code but hesitation. Old valve and replacement vacuum solenoid, no fault code and no hesitation.

[Bogwoppit]

Have you tried cleaning out the small bore metal pipework that supplies the EGR with gasses from the turbo?

 

When I had this fault (BLT 130pd Fabia), it was caused by a restriction in this pipe work. A previous owner had fitted a gasket with a Ø9.5mm hole to try and solve the 'BLT' stutter/hesitation problem. I drilled this out to Ø11mm and I have never seen the error code again in the last 4 years.

[andy-fisher]

I have decided that my particular fault was the vacuum solenoid. I have done many miles and all is still well in the Octy.

 

I believe that the vacuum solenoid was not delivering  enough vacuum to open the EGR valve enough and so throwing up a fault code. I hope this little investigation helps another owner with similar problems. My only real advice is don't buy cheap Chinese EGR valves and don't always assume it's the valve itself. My original one is back on the car and has covered 191,000 miles (allowing for the miles I did with the new one).

[jharv]

Hi andy-fisher,

Bit of an old thread I know but I have been following your admirably tenacious thread re: poor EGR flow as I have had exactly the same problem with my Octavia. Including limp mode, which I seem to have sorted with the help of fuel tank additives and driving in low gears like a lunatic to burn off all the coke in the air intake and EGR system.

 

Anyway today I fitted a £20 vacuum solenoid sourced from "our best friend" Ebay and BINGO! So far and touch wood the dreaded light has not reappeared!

 

One thing I noticed on the old Vac unit I took out is that two of the ports on it seem to be full of black stuff, each port has a little filter doesn't it, could these choked up little filters be that problem?

If I CBA and assuming the fix is indeed permanent I may just clean the filters and re-fit the unit to see?

 

So I took a piccy of the old vacuum vac unit, the photo vaguely shows the blackness of the gunk in the filters of the two right hand ports on the shot.

 

So Andy in anticipation, sincere thanks,

 

[jaz0710]

Thank you same issue on mine you forum helped thank you so much